The present invention relates to a system and method for detecting a cold engine state using a plurality of engine temperatures.
In the control of internal combustion engines, the conventional practice utilizes electronic control units, volatile and non-volatile memory, input and output driver circuitry, and a processor capable of executing a stored instruction set, to control the various functions of the engine and its associated systems. A particular electronic control unit communicates with numerous sensors, actuators, and other control units necessary to effect various control and information functions of the engine and/or vehicle.
Various sensors are used to detect engine operating parameters which may affect control of the engine and/or vehicle. However, many engine operating parameters or conditions are not directly measured or sensed due to the associated cost and/or availability of suitable sensors relative to the perceivable improvement in engine control. These parameters or conditions may be sensed or measured indirectly by sensing a related process or parameter using other sensors, or may be calculated or inferred. For example, torque sensors, while available, are not often used in vehicular applications. Likewise, it may be desirable to determine peak combustion temperature or pressure to improve the efficiency and reduce emissions related to the combustion process. As is known, lower than optimal combustion temperatures may result in white smoke while higher combustion temperatures result in increased production of oxides of nitrogen, and may result in engine damage if excessive. However, the harsh environment present within the cylinders is generally not amenable to temperature and/or pressure sensors for production use.
Temperature sensors are commonly used to detect the temperature of various engine and/or vehicle fluids (including air) to control associated engine components, including valves, heaters, shutters, and various other mechanisms. As is known, ambient and operating temperature variations may present a number of challenges in controlling the engine. Temperature-related complications may include fuel coagulation, insufficient coolant circulation, and increased exhaust emissions, among others. Conventional engine systems use the engine coolant temperature or engine oil temperature to activate various engine mechanisms in an effort to improve engine performance. However, a single fluid temperature measurement is not necessarily indicative of the current engine operating conditions which may be used to control one or more engine and/or vehicle devices. As such, it would be desirable to provide a system and method for detecting a cold engine based on signals from a plurality of engine temperature sensors.
It is therefore an object of the present invention to provide a method and system for detecting cold engine operation based on a plurality of engine fluid temperatures.
Another object of the present invention is to provide a system and method for detecting cold engine operation based on at least two fluid temperatures selected form the group including coolant temperature, intercooler temperature, and engine air temperature.
Another object of the present invention is to provide a system and method for providing a signal indicating cold engine operation only while the engine is idling.
An additional object of the present invention is to provide a cold engine output signal used to control one or more auxiliary devices based on a plurality of engine fluid temperatures.
A further object of the present invention is to provide a system and method for increasing combustion temperature when cold engine operation is detected by increasing parasitic loads on the engine.
A still further object of the present invention is to reduce or eliminate white smoke by activating one or more auxiliary devices to increase engine power resulting in increased combustion temperatures when cold engine operation is detected.
Yet another object of the present invention is to provide a customer configurable cold engine output signal based on a plurality of fluid temperatures.
A further object of the present invention is to provide a cold engine output signal based on a plurality of fluid temperatures each having corresponding temperature thresholds which can be used to adjust the sensitivity of the signal to any one or more of the constituent fluid temperatures.
In carrying out the above objects and other objects and features of the present invention an engine controller and computer readable storage medium include instructions for detecting cold engine operation and providing a cold engine output signal for use in engine and/or vehicle control by determining at least two fluid temperatures and providing an output signal based on the at least two temperatures. Preferably, an engine coolant temperature, an intercooler temperature, and an engine air temperature are determined via appropriate temperature sensors. In one embodiment, the cold engine output signal is activated or asserted if any one of the at least two fluid temperatures is below a corresponding temperature threshold. The cold engine output signal is deactivated when all of the fluid temperatures are above corresponding temperature thresholds (with appropriate hysteresis). An optional user-selectable parameter provides for actuation of the cold engine output only during idle.
A system for detecting cold engine operation and providing a cold engine output signal for use in engine control includes a plurality of engine temperature sensors for providing an indication of corresponding fluid temperatures. Preferably, the temperature sensors include an engine coolant temperature sensor for measuring an engine coolant temperature, an intercooler temperature sensor for measuring an intercooler temperature, and an engine air temperature sensor for measuring an engine air temperature. The system also includes a microprocessor in communication with the temperature sensors for determining whether at least one of the temperatures is below a corresponding temperature threshold. The electronic control unit includes control logic for generating a cold engine output signal if any of the fluid temperatures is below its corresponding temperature threshold. The electronic control unit also includes control logic for deactivating or de-energizing the cold engine output signal when all of the fluid temperatures are above their corresponding temperature thresholds. Optional control logic activates the cold engine output only when a cold engine condition is detected and the idle governor is active, i.e. the engine is idling.
The advantages accruing to the present invention are numerous. For example, the present invention enables the engine controller to more accurately detect cold engine operation to activate various engine and/or vehicle mechanisms based on the cold engine status. The present invention may be used to reduce white smoke caused by lower than desired combustion temperatures by detecting cold engine operation and controlling auxiliary devices to increase engine load to increase combustion temperatures. Multiple temperature sensors with corresponding programmable thresholds provide increased control versatility by providing a system which can activate cold engine start mechanisms such as coolant heating systems, extra parasitic loads, shutters or exhaust (engine) brakes. Independently selectable temperature thresholds or limits may be used to adjust the response of the cold engine output based on one or more of the constituent fluid temperatures.
The above objects and other objects, features, and advantages of the present invention are readily apparent from the following detailed description of the best mode for carrying out the invention when taken in connection with the accompanying drawings.